Method and means for abrading lenses



Sept. 6, 1938. K. c. BURROUGHS 2,129,522

METHOD AND MEANS 'FOR ABRADING LENSES Filed 001;. 9, 1955 INVENTOR KENNETH C. BURROUGHS I Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE METHOD AND MEANS FOR- ABRADING LENSES Kenneth C. Burroughs, Rochester, N. Y., assignor to Banach & Lomb Optical Company, Rochester, N. Y., a corporation of New York Application October 9, 1935, Serial No. 44,24!

6 Claims. (Cl. 51-278) This invention relates to the lens grinding and tially the same asthe area of the surface of the polishing art wherein an abrading tool'or lap lensto be ground or.polishe'd.'., The spindle i4 is is moved over the surfaceof a lens to grind or inclined, as shown in Fig.1, so that thegtool i3 polish it. overlies the lens L with the center of rotation of The invention is an improvement over the inthe tool positioned substantially at the edge of vention disclosed and claimed in application the lens L.

Serial No. 433,934, filed March '7, 1930, by Carl According to the present invention, the tool i3 E. Anderson for a Method and means for abradis slightly eccentr c n the Shaft and s. ing lenses, now Patent No. 2,105,175, dated Jan. ing ro a m es w n. the Positions indi- 11, 1938. It is quite difilcult mechanically to located at I! and i3" in Fig. 2. As stated a ove. 10 cats the tool and lens of that application so that when the edge of the tool contacts the center of the edge of the tool passes exactly over the center the lens, and the edge o t lens. the Center Of of the lens. Unless the tool and lens are so 10- the tool, itl' q great delicacy of djust e cated, the resultant lens will have either a raised to void ind ng the ce ter of t e le s eith r 1 spot in the center due to insufficient abrading twice or not at all. By making the tool eccen- 1 action, or will have a depressed spot due to double tric on the shaft ll, the am u of b ad n abrading action. The only alternatives distion at the center of the lens can be regulated. closed by Anderson for preventing this dimculty, It is also possible to obtain the same result by are the accurate positioning of the lens and tool oscillating the shaft ll about the center of curvaor the oscillating of the tool shaft and tool across im uring the rot tion of th tool- Th sy 20 the lens. Both of these obviously present mehowever, introduces difficulties of mechanical chanical difliculties. construction so that the eccentric positioning One of the objects of the present invention is of the tool is preferable. to provide a method and means for abrading The lens L and tool I: are rotated at the same .25 lenses wherein the tool will grind the lens unispeed in opposite directions, as indicated by the formly and will be worn away in a substantially arrows in Fig. 2, or they may be rotated in the uniform manner over its entire area. Another same direction. The tool and lens being of subobject is to provide a method and means for stantially the same diameter and area and'rotatabrading lenses wherein the tool is prevented ing at substantially the same speeds, the abrading from grinding high or low target spots in the action will be uniform over the entire surfaces of 30 center of the lens. These and other objects and the lens and tool. The tool will thus wear away advantages reside in certain novel features of uniformly without losing its curve so that a large construction, arrangement and combination of number of lenses may be ground without the neparts and in my improved method, as will hereincessity for truing up the tool.

5 after be more fully set forth and pointed out in The fundamental principles underlying the the appended claims. present invention are substantially the same as Referring to the drawing: those underlying the invention disclosed in the Fig. 1 is a sectional view of an apparatus emabove-mentioned application, Serial No. 433,934 bodying my invention. flied March '1, 1930 by Carl E. Anderson, for a -i() Fig. 2 is a schematic diagram illustrating the Method and means for abrading lenses. Accord- 40 overlapping relation between the tool and the ing to the present invention, however, the abradlens. ing tool is mounted eccentrically and the necessity One embodiment of this invention is illustrated of delicate or changing adjustments of the posiin the drawing wherein L indicates a lens blank tion of the tool, avoided.

which is to be operated upon. The blank L is From the foregoing it will be apparent that I 45 mounted, by any suitable means, upon a block or am able to attain the objects of my invention chuck l0 which is carried by a spindle II and and provide improved method and means for adapted to be rotated through the application of abrading lenses wherein the tool will grind the suitable power to the pulley ii. A suitable lens uniformly and will be worn away in a sub- 0 abrading tool or lap i3 is carriedby the spindle stantially uniform manner over its entire area. it so that it may be rotated or driven by a belt Various modifications can, of course, be made or other means through the pulley IS. without departing from the spirit of my inven- The diameter of the abrading tool I3 is subtion or the scope of the appended claims. stantially equal to the diameter of the lens L so I claim:

that the area of the abrading surface is substan- 1. A method of abrading lenses which com- 55 prises rotating an abrading tool in contact with a lens having substantially the same diameter as the abrading surface of the tool, holding said tool eccentrically with its abrading surface contacting said lens and with the center of rotation of the tool positioned substantially at the edge ofthe lens, and rotating said lens at substantially the same speed of rotation as the tool.

2. A method of abrading a lens having a substantially spherical surface which comprises placing in contact with said surface an abrading tool having a spherical surface which has substantially the same diameter and area as the surface of the lens, rotating said lens about an axis concentric with said lens and rotating said tool at substantially the same speed as said lens about an axis eccentric to said tool, the axis of rotation of said tool lying substantially in a line passing through the edge of said lens.

3. Lens abrading apparatus comprising a'lens carrying shaft, means for mounting a lens concentrically on said shaft, a tool carrying shaft positioned with its axis substantially at the edge of said lens, a tool having substantially the same area and diameter as said lens, means for mounting said tool eccentrically on said tool carrying shaft, and means for rotating said two shafts at substantially the same speed.

4.'Lens grinding means comprising a spindle carrying a block for supporting a lens, a second spindle mounted above the first spindle and in angular relation thereto, an abrading tool eccentrically fixed to said second spindle, said tool having a substantially continuous spherical surface whose area and diameter are substantially the same as the area and diameter of the lens, said tool being positioned in contact with the lens with its center of rotation substantially at the edge of said lens and means for rotating said spindles at substantially the same speeds.

5. A method of abrading lenses which comprises placing a tool in contact with a lens, rotating said tool about an axis which is eccentric to said tool and which passes adjacent the edge of said lens and rotating said lens at substantially the same speed as said tool.

6. A method of abrading lenses which comprises placing a tool in contact with a lens, rotating said tool about an axis which is eccentric to said tool and which passes adjacent the edge of said lens and rotating said lens at substan-. tially the same speed as said tool about an axis which is concentric to said lens.

KENNETH C. BURROUGHS. 

